projectionEngineDirectory

The directory of the Projection Engine files on the local file system. This property should only be set upon process startup - a suitable point could be after license or license keys, but before any use of maps, maps views, scene views, or any other functionality that may involve geometry or projection functionality.

Projection Engine data files are available in the downloads area of developers.arcgis.com[https://developers.arcgis.com/downloads/#pedata] (requires login).